Morphological responses of the rainbow trout (Oncorhynchus mykiss) gill to hyperoxia, base (NaHCO3) and acid (HCl) infusions

Greg G. Goss, Chris M. Wood, Pierre Laurent, Steve F. Perry

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


Marked morphological responses occur in the gills of freshwater rainbow trout in response to experimental acid-base disturbance and these responses play an important role in acid-base correction. Compensated respiratory acidosis induced by 70h exposure to environmental hyperoxia (elevated water PO2) caused a 33% decrease in branchial chloride cell fractional surface area (CCFA). Metabolic alkalosis induced by normoxic recovery (6h) from hyperoxia (72h) caused a 50% increase in CCFA, whereas metabolic alkalosis induced by infusion (19h) of NaHCO3 caused a 70% rise. However, the largest increase (135%) in CCFA was seen in response to infusion (19h) of HCl. NaCl infusion had no effect. A particular goal was to assess the relative importance of changes in CCFA vs. changes in internal substrate (HCO3-) availability in regulating the activity of the branchial Cl-/HCO3- exchange system. For each of the experimental treatments, the accompanying blood acid-base status and branchial transport kinetics (Km, Jmax) for Cl- uptake had been determined in earlier studies. In the present study, a positive linear relationship was established between CCFA and JCl-max in individual control fish in the absence of an acid-base disturbance. By reference to this relationship, observed changes in JCl-max during metabolic acid-base disturbances were clearly due to changes in both CCFA and internal substrate levels (plasma [HCO3-]) with the two factors having approximately equal influence.

Original languageEnglish (US)
Pages (from-to)465-477
Number of pages13
JournalFish Physiology and Biochemistry
Issue number6
StatePublished - Mar 1 1994


  • acid-base
  • chloride cell
  • fish
  • J
  • K
  • kinetics
  • morphology

ASJC Scopus subject areas

  • Physiology (medical)
  • Physiology
  • Biochemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Aquatic Science


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